A new style of test mule has begun running around Ford's development centers, perhaps offering the first signs that testing has begun on Ford's car-based Explorer. The rough test mules (we've now seen several running the streets of Dearborn) are a mix of Ford Taurus X and Ford Flex, but there are some telling alterations, raising the prototype's ride-height, along with a higher cowl, and rigged A-pillars to accommodate what appears to be a more steeply-raked windshield. There are also clear signs around the rear hatch and roof rails that the platform has been widened. While the front clip is pure Ford Flex, the lowest slat of the Flex's three-bar grille has been removed, perhaps to better approximate airflow of the next Explorer's grille. Ford also used the Taurus X body on mules for the Ford Flex and Lincoln MKT, but those mules had additional length added to their wheelbases. This latest mule features no such additions, suggesting that this new model will be shorter than the Flex for a more fuel-friendly footprint. Ford confirmed earlier this year that the Explorer would be ditching its body-on-frame SUV construction in favor of a new unibody, car-based approach for greater fuel-efficiency. The Explorer's new direction was previewed by Ford's Explorer America concept at the 2008 North American International Auto Show, and the general proportions of these latest mules seem to adequately approximate that concept. The new unibody Explorer crossover is expected to reach the market in 2010.